I am using Angular 6 and I have a simple div and want to set the background color of this div from inside the template. This works fine when passing normal colors. But this does not work with CSS Variables.
This example works
<div [style.background]="'red'">...</div>
This example does not work
<div [style.background]="'var(--some-css-var)'">...</div>
You have to use ngStyle
<some-element [ngStyle]="{'background-color': styleExp}">...</some-element>
In order to bind a style property to a CSS variable in the HTML template, the CSS variable expression var(...) must be sanitized. You can define a custom pipe:
import { Pipe, PipeTransform } from '@angular/core';
import { DomSanitizer, SafeStyle } from '@angular/platform-browser';
@Pipe({
name: 'safeStyle'
})
export class SafeStylePipe implements PipeTransform {
constructor(private sanitizer: DomSanitizer) { }
transform(value: string): SafeStyle {
return this.sanitizer.bypassSecurityTrustStyle(value);
}
}
and use it in the HTML template:
<div [style.background-color]="'var(--some-css-var)' | safeStyle"></div>
<div [style.background-color]="bkColor | safeStyle"></div>
bkColor = "var(--some-css-var)";
See this stackblitz for a demo.
ngStyle instead?
[ngStyle]="{ 'background-color': 'var(--dy-color-2)' }"ngStyle with a CSS variable (I thought @GurvinderGuraya gave it as a workaround). You can pick the solution that you prefer then. If sanitizing is not needed with ngStyle, then that would be a simpler solution.You can do it in 2 ways
use pipe that get a string and return some color code code.
<div [style.background-color]="someString | colorSetter"></div>
add to the html tag a dynamic class for example:
<div class="my-div" [class]="someClassName"></div>
and in the scss add the options
scss:
.my-div{
&.optoin1{
background-color:red;
}
&.optoin2{
background-color:black;
}
&.optoin3{
background-color:green;
}
&.optoin4{
background-color:yellow;
}
}
